1. Field of the Invention
This invention relates to clutch mechanisms used in manually-controlled automotive transmissions for transmitting power from the engine to the road wheels.
2. Description of Prior Developments
An example of a self-aligning clutch release drive connection is shown in U.S. Pat. No. 4,276,974 to Ladin which discloses a carrier sleeve slidably mounted on a fixed tubular shaft for supporting an anti-friction bearing. A non-rotating race of the anti-friction bearing is adapted to engage an actuating fork operated by a clutch pedal while a rotating race engages an array of radially extending clutch release levers. When the clutch pedal is depressed, the actuating fork exerts an operating force on the non-rotating race which transmits the force via the rotating race to the inner ends of the clutch release levers thereby swinging the levers in unison so as to disengage the clutch.
Because the clutch actuating fork typically pivots through an arc, a radial component of force may be transmitted to the carrier sleeve. This can cause increased resistance to clutch pedal actuation and can increase the wear rate of the bearing carrier sleeve and tubular shaft upon which the carrier reciprocates. In extreme cases, excessive wear and friction between the sleeve and shaft can generate such high actuation loads that the clutch release system can fail.
In order to achieve a smooth, noiseless, wear-free clutch disengagement action, the clutch disengagement levers should be operated in unison and radial loading between the carrier sleeve and its mounting shaft should be minimized. This requires that the rotating bearing race exert substantially the same operating force on each declutching lever and that radial loads from the pivoting actuating fork be reduced or eliminated. In some cases this may be difficult to achieve, due to manufacturing variances and frictional interferences between the support shaft, non-rotary race and actuating fork.
A typical approach to partially solving the above-noted problems is to allow the clutch release bearing to coaxially align itself with the clutch disengagement levers. An example of such a bearing is shown in U.S. Pat. No. 4,276,974 which includes a mechanism for supporting a non-rotating bearing race on a carrier sleeve so that the rotating race can have its end face in simultaneous engagement with all of the declutching levers in spite of oblique forces imposed on the anti-friction bearing by an actuating yoke and slidable sleeve. The support mechanism includes an annular wave spring mounted between the carrier sleeve and the non-rotating race member of the anti-friction bearing.
A different approach to solving clutch release bearing alignment problems is shown in U.S. Pat. No. 4,997,075 which provides a shiftable annular guide plate for movably engaging the clutch operating fork. The guide plate is mounted on rollers which allow the guide plate to move perpendicular to the axis of the clutch release bearing during clutch actuation.